| 61. |
- Lindahl, Mikael, et al.
(författare)
-
Short term plasticity within the basal ganglia - a systems level computational investigation
- 2011
-
Ingår i: BMC Neuroscience. - 1471-2202. ; 12:Suppl 1, s. P145-
-
Tidskriftsartikel (refereegranskat)abstract
- Striatal direct pathway medium spiny neurons (MSNs) converge, with inhibitory synapses onto output nuclei substantia nigra reticulata (SNr), which keep neurons in the thalamus, superior colliculus and pendunculopontine nuclei under tonic inhibition[1]. Recent experimental findings[2] have found short term facilitation in MSN synapses onto SNr neurons. We investigate the functional consequences of these findings using a basal ganglia system level model, with spiking MSNs modeled according to Izhikevich’s simple model[3] and with facilitating synapses[4] fitted to data in[2]. The model is implemented in the NEST[5] simulator. We quantify how striatal populations of MSNs can control activity in SNr neurons, and to what extent this depends on having weak static, strong static and facilitating synapses between MSNs and SNr neurons. Our simulation experiments predict that facilitating synapses allow baseline firing of presynaptic MSNs without suppressing target SNr neurons, while burst activation of only a few of these presynaptic striatal neurons can suppress the activity of one SNr neuron. This is in accordance with extracellular recordings in awake animals[6], where task dependent activity is transferred from a broad striatal population to a smaller subpopulation, responding increasingly stronger during learning of a task dependent behavior.
|
|
| 62. |
|
|
| 63. |
|
|
| 64. |
|
|
| 65. |
|
|
| 66. |
|
|
| 67. |
|
|
| 68. |
- Adelöf, Julia, 1990, et al.
(författare)
-
PA28αβ overexpression enhances learning and memory of female mice without inducing 20S proteasome activity
- 2018
-
Ingår i: BMC Neuroscience. - : Springer Science and Business Media LLC. - 1471-2202. ; 19:1
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The proteasome system plays an important role in synaptic plasticity. Induction and maintenance of long term potentiation is directly dependent on selective targeting of proteins for proteasomal degradation. The 20S proteasome activator PA28αβ activates hydrolysis of small nonubiquitinated peptides and possesses protective functions upon oxidative stress and proteinopathy. The effect of PA28αβ activity on behavior and memory function is, however, not known. We generated a mouse model that overexpresses PA28α (PA28αOE) to understand PA28αβ function during healthy adult homeostasis via assessment of physiological and behavioral profiles, focusing on female mice. RESULTS: PA28α and PA28β protein levels were markedly increased in all PA28αOE tissues analyzed. PA28αOE displayed reduced depressive-like behavior in the forced swim test and improved memory/learning function assessed by intersession habituation in activity box and shuttle box passive avoidance test, with no significant differences in anxiety or general locomotor activity. Nor were there any differences found when compared to WT for body composition or immuno-profile. The cognitive effects of PA28αOE were female specific, but could not be explained by alterations in estrogen serum levels or hippocampal regulation of estrogen receptor β. Further, there were no differences in hippocampal protein expression of neuronal or synaptic markers between PA28αOE and WT. Biochemical analysis of hippocampal extracts demonstrated that PA28α overexpression did not increase PA28-20S peptidase activity or decrease K48-polyubiquitin levels. Instead, PA28αOE exhibited elevated efficiency in preventing aggregation in the hippocampus. CONCLUSIONS: This study reveals, for the first time, a connection between PA28αβ and neuronal function. We found that PA28α overexpressing female mice displayed reduced depressive-like behavior and enhanced learning and memory. Since the positive effects of PA28α overexpression arose without an activation of 20S proteasome capacity, they are likely independent of PA28αβ's role as a 20S proteasome activator and instead depend on a recognized chaperone-like function. These findings suggest that proteostasis in synaptic plasticity is more diverse than previously reported, and demonstrates a novel function of PA28αβ in the brain.
|
|
| 69. |
- Balkenius, Anna, et al.
(författare)
-
Multimodal interaction in the insect brain
- 2016
-
Ingår i: BMC Neuroscience. - : Springer Science and Business Media LLC. - 1471-2202. ; 17
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe magnitude of multimodal enhancement in the brain is believed to depend on the stimulus intensity and timing. Such an effect has been found in many species, but has not been previously investigated in insects.ResultsWe investigated the responses to multimodal stimuli consisting of an odour and a colour in the antennal lobe and mushroom body of the moth Manduca sexta. The mushroom body shows enhanced responses for multimodal stimuli consisting of a general flower odour and a blue colour. No such effect was seen for a bergamot odour. The enhancement shows an inverse effectiveness where the responses to weaker multimodal stimuli are amplified more than those to stronger stimuli. Furthermore, the enhancement depends on the precise timing of the two stimulus components.ConclusionsInsect multimodal processing show both the principle of inverse effectiveness and the existence of an optimal temporal window.
|
|
| 70. |
- Belic, Jovana, et al.
(författare)
-
The role of striatal feedforward inhibition in propagation of cortical oscillations
- 2017
-
Ingår i: BMC Neuroscience. - Antwerpen. - 1471-2202. ; 18, s. 91-91
-
Tidskriftsartikel (refereegranskat)abstract
- Fast spiking interneurons (FSIs) and feedforward (FF) inhibition are a common property of neuronal networks throughout the brain and play crucial role in neural computations. For instance, in the cortex FF inhibition sets the window of temporal integration and spiking and thereby contributes to the control of firing rate and correlations [1]. In the striatum (the main input structure of the basal ganglia) despite their high firing rates and strong synapses, FSIs (comprise 1–2% of striatal neurons) do not seem to play a major role in controlling the firing of medium spiny neurons (MSNs; comprise 95% of striatal neurons) [2] and so far, it has not been possible to attribute a functional role to FSIs in the striatum. Here we use a spiking neuron network model in order to investigate how externally induced oscillations propagate through striatal circuitry. Recordings in the striatum have shown robust oscillatory activity that might be in fact cortical oscillations transmitted by the corticostriatal projections [3–5]. We propose that FSIs can perform an important role in transferring cortical oscillations to the striatum especially to those MSNs that are not directly driven by the cortical oscillations. Strong and divergent connectivity of FSIs implies that even weak oscillations in FSI population activity can be spread to the whole MSN population [6]. Further, we have identified multiple factors that influence the transfer of oscillations to MSNs. The variables such as the number of activated neurons, ongoing activity, connectivity, and synchronicity of inputs influence the transfer of oscillations by modifying the levels of feedforward and feedback inhibitions suggesting that the striatum can exploit different parameters to impact the transfer of oscillatory signals.References1. Isaacson, J. S., & Scanziani, M. (2011). How inhibition shapes cortical activity. Neuron, 72(2), 231–243. 2. Berke, J. D. (2011). Functional properties of striatal fast-spiking interneurons. Frontiers in systems neuroscience, 5.3. Belić, J. J., Halje, P., Richter, U., Petersson, P., & Kotaleski, J. H. (2016). Untangling cortico-striatal connectivity and cross-frequency coupling in L-DOPA-induced dyskinesia. Frontiers in systems neuroscience, 10.4. Berke, J. D. (2009). Fast oscillations in cortical‐striatal networks switch frequency following rewarding events and stimulant drugs. European Journal of Neuroscience, 30(5), 848–859.5. Boraud, T., Brown, P., Goldberg, J. A., Graybiel, A. M., & Magill, P. J. (2005). Oscillations in the basal ganglia: the good, the bad, and the unexpected. In The basal ganglia VIII (pp. 1–24). Springer US.6. Belić, J. J., Kumar, A., & Kotaleski, J. H. (2017). Interplay between periodic stimulation and GABAergic inhibition in striatal network oscillations. PloS one, 12(4), e0175135.
|
|
